1. Field of the Invention
The present invention relates to a wireless communication system that can select a network for connecting a wireless terminal.
2. Description of the Related Art
There is a wireless communication system that covers communication areas by cells formed by wireless base stations to allow a wireless terminal to communicate in the communication areas. For example, in WiMAX (Worldwide Interoperability for Microwave Access), cells cover communication areas to allow communications in various places.
Providers construct networks, such as a WiMAX network, respectively. Therefore, communication areas of networks may overlap in the same area. The provider of each network independently sets the service area, provided services, fee, etc. Therefore, the service area, provided services, fee, etc., may differ in each network. The communication quality of the wireless line may also be different from one network to another network even in the same location since the arrangements of the wireless base stations are different from one network to another network.
However, the user usually subscribes to the network of a provider. Therefore, the wireless terminal connects to the subscribed network when the user is at a location where the communication areas of networks overlap. Therefore, the wireless terminal does not always connect to the network most suitable for the requested conditions. For example, the wireless terminal may not be able to connect to a network having a lower fee, a network that provides a user's desired service, or a network in which the communication quality of the wireless line is excellent.
Consequently, Japanese Patent Laid-Open Nos. 2005-318235 and 2008-131346 disclose techniques of a communication terminal that selects and connects to an optimal network among networks.
Japanese Patent Laid-Open No. 2005-318235 describes that a communication terminal stores the contents of communication services of IP (Internet Protocol) phones and selects a communication service having the lowest price based on the fee per packet, etc.
Japanese Patent Laid-Open No. 2008-131346 describes that a monitoring control server arranged separately from the communication terminal always changes the communication path. According to the technique, the monitoring control server includes: test packet transmission instructing means for transmitting a test packet transmission instruction; transmission quality measuring means for receiving the reception result of a test packet to obtain transmission qualities of communication paths; communication path selecting means for selecting a communication path based on the transmission qualities of the communication paths; and communication path instructing means for transmitting a communication path setting instruction. The communication terminal includes: test packet transmitting means for transmitting a test packet; test packet reception result transmitting means for transmitting a reception result of the test packet; and communication path setting means for setting a communication path.
However, the techniques described in Japanese Patent Laid-Open Nos. 2005-318235 and 2008-131346 do not take into consideration the fact that the indexes for selecting a network include indexes that always change, such as the transmission quality of the communication line, and indexes that rarely change, such as service areas and the fee per packet. Therefore, a network may not be appropriately selected in a method corresponding to the properties of the indexes.
In Japanese Patent Laid-Open No. 2005-318235, the communication terminal stores the contents of communication services and selects a communication service based on the fee per packet, etc. However, a change in the setting of network services, such as service area and fee per packet, cannot be easily notified to all communication terminals in real time. Therefore, the technique of Japanese Patent Laid-Open No. 2005-318235 does not select a network based on an appropriate method according to the indexes, and the communication terminal cannot appropriately select a network after the setting of the network services changes.